Device and method for the application of a sheet-like jointing means onto a contact area of a wafer

ABSTRACT

The invention concerns a device and a corresponding method for the jointing of wafers along their corresponding surfaces.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/078,136, filed Mar. 11, 2005, now U.S. Pat. No. 8,500,930, whichclaims priority from German Patent Application No. 10 2004 012 618.6,filed Mar. 12, 2004, said patent applications hereby fully incorporatedherein by reference.

FIELD OF THE INVENTION

The invention relates to a device and a method for the application of asheet-like jointing means onto a contact area of a wafer.

BACKGROUND OF THE INVENTION

The methods described in the prior art for the application of sheet-likejointing means onto a contact area of a wafer essentially take place asfollows.

The sheet-like jointing means are usually multi-layer films with amiddle layer, which provides for the jointing of the carrier wafer withthe product wafer. Protective films are arranged above and below thismiddle layer, in order that the multi-layer films can be used in aspace-saving manner during delivery and processing and the middle layerdoes not become jointed to itself and consequently could no longer beunrolled. These protective films also have the purpose of preventingcontamination of the middle film.

With the generic methods, the multi-layer film is first guided to thecarrier wafer. Along this path, the lower protective film is removed inorder that the middle layer, also referred to as the adhesive film, canbe brought into contact with the wafer. The carrier wafer—also referredto as the handling wafer—is made from very hard material, e.g. sapphire.Once the film has been brought onto the carrier wafer, a blade is usedto cut along the edge of the carrier wafer, so that the carrier waferand the film, now consisting solely of the middle layer and upper layer,are jointed without overlapping portions.

The carrier wafer thus obtained with the applied film is then introducedfor further processing into known bonding systems, in which the upperprotective layer is removed and the product wafer is bonded with thecarrier wafer.

The critical point in the methods previously described in the prior artis the cutting of the sheet-like jointing means along the edge of thevery hard carrier wafer. If a blade is used for this, the latter alreadyhas to be replaced after a few passes, because it is blunt. This thuscauses high material wear and downtimes with the equipment.

If, on the other hand, a laser beam is used for cutting the film alongthe edge, the latter produces at the cutting edge a projecting border orbead, which subsequently hinders precise bonding.

When cutting along the edge, moreover, as soon as the blade has beenconveyed once around the wafer, film stripes arise with inaccuratecutting, which then hang out from the wafer face during furtherprocessing and can even get onto the wafer surface.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method and a device,with which wafers can be provided with an adhesive film in a low-costmanner without the possibility of strip formation.

The basic idea of the invention is to adapt the sheet-like jointingmeans (multi-layer film) beforehand to the shape and size of the contactarea of the carrier wafer and then to produce the contact between thejointing means and the wafer.

Insofar as mention is made of wafer in connection with the invention,this stands vicariously for any kind of sheet-like component that has tomake contact in a precise manner with a sheet-like jointing element.

The object mentioned is solved by a device for the application of asheet-like jointing element onto a contact area of a wafer, which hasthe following features:

-   -   a. a first device for receiving and, as necessary, moving the        sheet-like jointing element    -   b. a second device for receiving and, as necessary, moving the        wafer    -   c. alignment means    -   d. a control unit which brings about the following work steps        after one another:        -   i. alignment of the contact area of the sheet-like jointing            means with the contact area of the wafer by means of the            alignment means, the first device and the second device,            whereby the size of the sheet-like jointing element            essentially corresponds to the size of the contact area of            the wafer.        -   ii. bringing the contact area of the sheet-like jointing            means into contact with the contact area of the wafer.

The first device can be a chuck which receives the sheet-like jointingelement, for example by means of suction, and can freely move and rotatethe latter in the device.

The second device can also be one such chuck or a similar chuck, onwhich the carrier wafer lies. This chuck can be made of glass or anothertransparent material, in order that the alignment means can determine,through the latter, the position of the wafer on the second device andcan be arranged beneath the latter. Equally, however, the chuck can alsobe constituted by a non-transparent material and the position of thewafer determined in another way.

The sheet-like jointing means is first aligned by means of alignmentmeans with the contact area of the wafer, whereby the sheet-likejointing means already has the surface dimensions of the wafer. It mayeven be sensible to form the jointing means a very small amount, forexample 100 μm, smaller in diameter, so that the carrier wafer issubsequently contacted first with an edge contact. The horizontalalignment of the sheet-like jointing means precisely over the wafer alsolying horizontal on the second device is sensible.

The first device is then lowered, as a result of which the contact areaof the jointing means lying precisely over the contact area of thecarrier wafer is brought into contact with the latter.

In this way, a device is created which manages without a blade that hasto cut the jointing means along the wafer, as a result of which itfollows that an interruption in production to replace the blade is notnecessary during preparation of the wafer for the bonding process.Furthermore, it can no longer happen that strips, which arise whencutting along the wafer in the prior art, hinder the subsequentprocessing of the wafer or cause waste.

Optical detection means, which detect the position of the sheet-likejointing element and the wafer in a contactless manner and comprise atleast one, but preferably three, detection devices, ensure the exactalignment of the sheet-like jointing means with respect to the wafer orvice versa, in that they detect the relative position of the jointingmeans with respect to the wafer and relay this to the control unit,which then effects an alignment of the wafer precisely beneath thesheet-like jointing element.

The optical detection devices can be designed as microscopes, by meansof which a micrometer-precise alignment and subsequent contacting of thesheet-like jointing means with the carrier wafer can be achieved,without wear and waste products inside the device having to betransported away. The contamination of the usually sterile interior ofthe device is reduced to a minimum.

For the alignment of the wafer and the sheet-like jointing element, useis made of mechanical means which rotate and/or displace the respectivewafer as soon as corresponding signals are received from the controlunit.

The aforementioned problem is also solved by an accompanying method forthe application of a sheet-like jointing element onto a contact area ofa wafer, wherein the sheet-like jointing element is first broughtessentially to the size of the contact area of the wafer and the contactareas are then aligned with one another and brought into contact bymeans of a first device for receiving and, as necessary, moving thesheet-like jointing element and a second device for receiving and, asnecessary, moving the wafer and alignment means, whereby the course ofthe method is controlled by a control unit which is connected via activeconnections to the first and second device and to the alignment means.

A constituent part of the method according to the invention is thematching of the size of the jointing means to the size of the contactarea of the wafer. This can take place both inside the device describedabove with the aid of a punching device. Several pieces of film can alsobe punched simultaneously from an unwinding multi-layer film by means ofthis punching device. The advantage of punching-out consists in the factthat the wear is less compared with cutting and the punching-out cantake place much more rapidly. Various sizes of wafers can be catered forby means of different stamping punches.

The sheet-like jointing means can, however, also be purchased alreadypre-punched and introduced in this form into the device. This is also tobe assumed within the wording of the method.

With regard to further forms of embodiment in respect of the individualprocess steps, reference is made to the above explanations in connectionwith the device and to the following description of the figures.

Further features of the invention will emerge from the features of thesub-claims as well as the other application documents.

The invention will be explained in greater detail below with the aid ofan example of embodiment. The features described therein may be ofimportance for the implementation of the invention both individually aswell as in any combinations. This also applies to the features that havebeen mentioned above to describe the device and the method.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures in the drawing show the following in detail:

FIG. 1 a diagrammatic view of the device according to the invention

FIG. 2 a diagrammatic view of the device according to the invention withexpansion units

FIG. 3 a diagrammatic side view of the device according to the inventionwith expansion units

FIG. 4 a diagrammatic view of a preparation step.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows—very schematised—a control unit 6, which effects theperformance of the method according to the process steps described inthe above description in an exemplary configuration of the presentinvention.

Control device 6 is connected here by means of a first, second and thirdconnection 3 w, 4 w and 5 w respectively to a first device 3 forreceiving and, as necessary, moving a sheet-like jointing element 1, asecond device 4 for receiving and, as necessary, moving a wafer 2, andalignment means 5.

First device 3 and second device 4 are able, respectively, to movesheet-like jointing element 1 and wafer 2 with precision arbitrarilywithin the device. Movement is intended to mean traversing in allspatial directions as well as a rotation. The spatial arrangement of thedevices with respect to one another is merely by way of example. One ofthe two devices 3 or 4 can be designed rigid in a simplified form ofembodiment.

The receiving of wafer 2 on second device 4 and the receiving ofsheet-like jointing element 1 on first device 3 takes place in a mannerknown in the prior art, here by means of a Bernoulli connection.

Sheet-like jointing element 1 is a multi-layer film here, whichcomprises an upper and lower protective film 1 s and a middle jointingfilm 1 f, which is in separable contact with the protective film in eachcase with a contact area 1 k above and below. Lower contact area 1 kserves here for the jointing with the (carrier) wafer 2. Upper contactarea 1 k serves for the subsequent jointing of sheet-like jointingelement 1, jointed with carrier wafer 2, with a product wafer in thebonding. (not shown here).

Arranged beneath second device 4 are alignment means 5, which serve forthe alignment of carrier wafer 2 with respect to sheet-like jointingmeans 1. The geometrical arrangement of alignment means 5 inside thedevice is however to be regarded merely by way of example.

Optical detection means 7 serve both to detect the position ofsheet-like jointing element 1 and to detect the position of wafer 2 andhave two detection devices 8, two microscopes here. There can of coursealso be assigned to sheet-like jointing element 1 and to wafer 2 theirown detection devices 8 for detecting the position. Second device 4 istransparent in the present configuration of the invention, so that adetection of the position of wafer 2 is possible from beneath. This canbe seen by the dot-dashed line, which represents diagrammatically thedetection beam.

FIG. 2, moreover, shows a punching device 10 for punching out sheet-likejointing element 1. The sheet-like jointing elements are punched outwith the punching device from a multi-layer film, which is delivered asa roll, and are then fed to the device represented in FIG. 1. Adiagrammatic sectional side view of the punching device is shown in FIG.4. First device 3 for receiving and, as necessary, moving sheet-likejointing element 1 is aligned over the multi-layer film and a stampingpunch 11 of punching device 10 and lowered down to the protective film.

Sheet-like jointing element 1, which essentially corresponds in size,i.e. the surface area, to contact area 2 k of wafer 2, is then punchedout. No strips at the edge of sheet-like jointing element 1 can beformed due to the punching-out, as often occurs with the conventionalcutting of sheet-like jointing element 1 along the edge of wafer 2. Thedevice according to the invention also operates, of course, with alreadypre-punched or already punched-out sheet-like jointing means 1. Thepunching-out process just described is then partially or whollydispensed with.

Lower protective film 1 s of sheet-like jointing element 1 is pulled offby means of a film pull-off device 9 v.

Stamping punch 11 of punching device 10 is lowered again and firstdevice 3 is moved together with sheet-like jointing element 1 into aposition over alignment means 5, where the following alignment processbegins. The exact position of sheet-like jointing element 1 is detectedand stored, which takes place either in storage means in alignment means5 or in storage means in control unit 6. The data can in each case betransmitted via connections 3 w, 4 w and 5 w.

The edge of sheet-like jointing means 1 and of wafer 2 respectivelyserves in the present case to detect the position, said edge beingdetected and processed by means of image recognition. The detection canalso take place by means of adjustment marks made on sheet-like jointingmeans 1 and/or wafer 2, by means of which adjustment marks the preciseposition can be calculated.

After the position has been stored, carrier wafer 2 is conveyed betweensheet-like jointing means 1 and alignment means 5, whereby contact areas1 k and 2 k lie opposite one another. Wafer 2 is now moved into exactlythe same position under the sheet-like jointing element, whereby it alsoinvolves the same rotation alignment. The wafer is aligned with thesheet-like jointing means here with the aid of a flattening of theotherwise rotation-symmetric body.

As soon as the correct position is reached, contact areas 1 k and 2 kare brought into contact. Contact area 1 k of the sheet-like jointingmeans is slightly smaller in the present configuration of the invention,so that the edge of the carrier wafer subsequently projects outwardsslightly in the finish-bonded wafer. Contact areas 1 k and 2 k arebrought into contact precisely at the centre of gravity of the areas, sothat a uniform step arises at the circumference.

First device 3 is then separated from sheet-like jointing element 1 andsheet-like jointing element 1 together with carrier wafer 2 undergoesfurther process steps. In the subsequent process, upper protective film1 s still remaining on sheet-like jointing element 1 is then removed bymeans of film removal means 9 n, in order that sheet-like jointingelement 1 can be conveyed together with carrier wafer 2 for bonding witha product wafer.

As a result of the invention thus configured, the punching, laminationand removal of the protective film from the multi-layer film is carriedout in one device. In addition, the high degree of wear on the bladesduring the cutting of the multi-layer film along the hard carrier-waferedge is no longer present. Stamping punches 11 can easily be replaced byothers, and this enables the use of a large number of shapes and sizesof wafers 2 and sheet-like jointing elements 1. Furthermore, no waste orcomparatively little waste is produced inside the device.

Having described the invention, the following is claimed:
 1. A devicefor the application of a sheet-like jointing element onto a contact areaof a wafer with the following features: a first holding device having asurface for receiving the sheet-like jointing element thereon; a secondholding device having a surface for receiving the wafer thereon, whereinthe surface of the first holding device and the surface of the secondholding device are movable relative to each other; a single detectiondevice that detects the position of a contact area of the wafer at apredetermined location and an outer peripheral edge of the sheet-likejointing element at the predetermined location; a control unit connectedto the first holding device, the second holding device and the singledetection device, the control unit programmed to provide commands to thefirst holding device, the second holding device and the single detectiondevice: to align the contact area of the sheet-like jointing elementwith the contact area of the wafer, whereby the size of the contact areaof the sheet-like jointing element essentially corresponds to the sizeof the contact area of the wafer, and to bring the contact area of thesheet-like jointing element into contact with the contact area of thewafer.
 2. The device according to claim 1, wherein the single detectiondevice is an optical detection device which detects the positions of thesheet-like jointing element and the wafer.
 3. The device according toclaim 2, whereby the optical detection device is a microscope.
 4. Thedevice according to claim 1, wherein the control unit includes a datastorage device connected to the first and second holding devices and thesingle detection device and the control unit is programmed such that:the sheet-like jointing element is moved by the first holding deviceinto a position over the single detection device, whereby the contactarea of the sheet-like jointing element is arranged in the direction ofthe single detection device; the position of the sheet-like jointingelement is stored in the data storage device of the control unit; andthe wafer is moved by the second holding device into a position betweenthe sheet-like jointing element and the single detection device, wherebythe contact area of the wafer is arranged in the direction of thecontact area of the sheet-like jointing element and parallel to thecontact area of the sheet-like jointing element, and whereby the contactareas are arranged precisely opposite one another.
 5. The deviceaccording to claim 1, wherein the contact area of the sheet-likejointing element is smaller than or equal to the contact area of thewafer.
 6. The device according to claim 1, further comprising a punchdevice to punch out the sheet-like jointing element to the appropriatesize.
 7. The device according to claim 6, wherein the punch deviceincludes a film removal device to remove a protective film from thesheet-like jointing element prior to a punching-out step.
 8. The deviceaccording to claim 1, wherein the sheet-like jointing element is ajointing film with two contact areas, whereby each contact area iscovered by a protective film, and whereby a film removal device isprovided, which removes the protective film from the sheet-like jointingelement prior to the contact area of the sheet-like jointing elementcoming into contact with a corresponding contact area of the wafer. 9.The device according to claim 1, wherein the control unit includes adata storage device connected to the first and second holding devices tostore the positions of the sheet-like jointing element and of the wafer.10. The device according to claim 1, wherein the single detection devicedetects the position of the outer peripheral edge of the sheet-likejointing element relative to the contact area of the wafer.